Solder bump doping to suppress undercooling
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Solution Overview
Problem
Conventional solder bumps suffer from the undercooling effect, leading to random solidification and degradation due to the difference in transition temperatures from solid to liquid and liquid to solid phases, which affects their quality.
Innovation Solution
A method is introduced to form metal bumps by providing a substrate, forming a solder bump, and then introducing minor elements adjacent to its surface, followed by a re-flow process to drive these elements into the bump, improving its properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solder bumps are formed without adding minor elements, then the manufacturing process is simple, but the quality of solder bumps degrades due to undercooling effect and random solidification
Solution Approach 1:
The patent applies preliminary action by introducing minor elements (such as germanium, silver, or copper) into the solder bump material before the reflow process. This pre-preparation ensures that the minor elements are already in position to suppress undercooling and promote uniform solidification when the reflow process occurs, thereby improving solder bump quality without requiring complex post-processing steps.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition of the solder bump through the addition of minor elements. Specifically, the minor elements alter the solidification characteristics of the solder material, changing the temperature parameters and solidification behavior during the reflow process. This composition modification enables uniform solidification and eliminates the undercooling effect, improving reliability while maintaining process simplicity.
2Manufacturing precision
If minor elements are added to solder bumps to improve properties, then the quality and uniformity of solidification improve, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies merging by combining the introduction of minor elements with the existing reflow process. Instead of adding separate complex processing steps, the minor elements are introduced during or before the reflow operation, merging multiple functions (element introduction, heating, and solidification control) into a single integrated process step. This approach achieves uniform solidification while minimizing additional process complexity.
3Strength
If minor elements such as germanium, silver, and copper are added to metal bumps, then mechanical strength and electro-migration resistance improve, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent applies parameter changes by modifying the material composition parameters of the metal bump through the addition of minor elements. The specific elements (germanium, silver, copper) and their concentrations are carefully selected to optimize mechanical strength and electro-migration resistance. This composition parameter modification achieves improved material properties while the doping is integrated into the existing reflow process, limiting the increase in overall process complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The introduction of minor elements enhances the quality of metal bumps by reducing the undercooling effect, resulting in more uniform solidification and improved mechanical and electro-migration resistance during bonding processes.
Implementation Method 1
a re-flow process is then performed to the solder bump to drive the minor element into the solder bump
Data Source
AI summary
A method of forming a device includes providing a substrate, and forming a solder bump over the substrate. A minor element is introduced to a region adjacent a top surface of the solder bump. A re-flow process is then performed to the solder bump to drive the minor element into the solder bump.